Splines vs. square tapers.

General
1

After not using my muni for a while (I’ve been using the 29-er and also had 125s on the muni to use it as a street machine) I put the 150 cranks back on and went for a ride.

I thought I may as well use it as a muni for once, and rode into the ‘Ponderosa’, a stretch of land that is mainly left to its own devices, with some rough trails and steep gradients.

Within ten minutes the handle felt loose and it turned out I’d snapped the seat base. About to ride it home I discovered the left crank had also come loose, so, for the first time ever, I had to wheel it home.

On the way I started to wonder if my faithful old Nimbus was reaching the end of its days, and what would be its replacement- another Nimbus or maybe the splined KH or Onza?

I’ve always been very happy with the Nimbus, and with its non splined cranks, but there seems to an assumption that, if you’re serious about muni, then a splined hub is the way to go.

However, having done a few thread searches, I wonder if that is true. I think I saw a reply by Roger Davies where he said he uses square taper hubs, and that splines are unnecessary if you’re not doing big drops.

Also, looking at splined models, the crank length options for muni seem to be 165-170mm only. As someone who uses 150s and who finds 170s to be uncomfortable and slow (admittedly I’ve only had brief goes on them) I find that a bit restrictive.

Also, the cranks themselves are consideraby more expensive than non splined ones (by a factor of 4).

One thing I dislike about square tapers is the messing around involved in changing them i.e. grease, hammering etc; but, from some posts I’ve seen, splined ones seem troublesome to remove as well.

I’ve fixed my Nimbus by fitting the Reeder handle to an old seat, and the crank looseness was probably cos of the recent switch, having tightened it up I had a long ride today and it’s fine again.

However, at some point I’ll have to get a new muni; whilst the KH looks nice and it’d be good to have the latest kit, I suspect that I’d get a Nimbus because I’ve found it to be reliable and a great muni, I also have the tools and knowledge of how to maintain it. I also think it unlikely that I’ll be doing high drops.

Here’s some questions on splined hubs/cranks.

  1. Is there any point to them if you’re not going to do long drops
  2. Any ideas about what will happen in the future eg will square taper hubs vanish like cottered cranks did, or, if munis popularity drops, will splined cranks dissapear
  3. Why no 150mm splined cranks
  4. Any other thoughts on splined/square taper hubs/cranks
2

I would also like to hear from people who’ve managed to break a Suzue or any other hardened non-splined hub, in particular the length of use and the sort of punishment it was subjected to. Thank you.

3

Dave- I have 170 profiles and i would never go any shorter. Sure i get passed up in the flats but the torque on steep uphills and steep rock faces is priceless!

BTW, there are 150 profiles.

Do Suzues count as hardened hubs? I’ve wrecked my share. I went through a hub (suzue) and a hand full of cranks on my United/monty trials. Back when i was using the monty i wasnt good at rolling out of drops so anything bigger than a 3 foot drop would usually mess something up.

I also had a shwinn muni that i cracked the suzue hub on while going down some rocks.

4

Is that 170s on a 26" or 24" or 24" with 3" tyre?

I currently ride a 24x3 and used 150s because I didn’t just use it for muni.

Now I’ve got into 29-er with 5" cranks and I’m thinking that I could use the 24x3 just for muni. On todays ride I started thinking maybe I should give 170s a go so I can tackle steeper stuff.

5

Sorry i wasnt more specific.

170 cranks on 24X3 muni. I mostly use it for muni; trials sometimes.

6

Re: Splines vs. square tapers.

[list=1]

  • There is a point to having splines even if you don't do large drops. The cranks and axle are more durable. They allow you to reposition the cranks easily, to change the most worn spots on the tire, prolonging the active life of your tire.
  • Square taper hubs may improve, and the fastening mechanism has recently been improved on the Unicycle.com ChroMoly hub. I doubt that MUni popularity will drop in a hurry.
  • Profile makes many different splined crank sizes, ranging from 145mm to 170mm (and bigger) in 5mm increments. You can get 140mm or 170mm KH cranks, and there is a possibility of more sizes to choose from in the future. Qu-ax makes even shorter splined cranks, I'm not sure of the details, maybe 125mm.
  • For a MUni or Trials uni, I think you should go for splined cranks and hub if you can afford it. They are much stronger and more convenient than square taper hubs and cranks. I do not regret getting 145mm and 170mm Profiles, it's so much better riding with cranks that aren't bent or loose. Square taper hubs have always given me problems, although I've never owned a hardened one yet.[/list=1]
    • 7

    I have a twisted Suzue hub at home. And alot of bent cranks in the trash to go with it.

    I was using it for trials, doing 3-4 foot drops. My form wasnt great but I seemed to bend cranks even if I was slightly off. The hub is twisted 4 or 5 degrees. I used it for 8 months before I invested in profiles.

    8

    There are two main reasons for going with splined cranks: strength and reliability.

    Square tapered cranks on a muni are unreliable. They will eventually come loose on you during a muni ride. Murphy’s Law makes sure that the crank comes loose when it is most inconvenient. Even if you carry a crank tool and a 14 mm socket, you can’t always fix it completely and get it tight enough while on the trail. You need to take it home where you can grease the taper and press the crank on again. When I was using a square tapered hub on my muni (a Pashley) I always brought crank tools with me and a spare crank nut. However, I still ended up walking back to the car more than once because the crank came loose and I couldn’t get it tight enough on the trail. The reliability alone makes splined cranks worth it for me. I hate wasting a ride because of a stupid mechanical failure.

    The other advantage is strength. Splined hubs and splined cranks are stronger. You’re not likely to break them.

    Old school muni was done with square tapered hubs and cranks. Broken hubs and broken cranks were common for the people doing aggressive riding. Aggressive riding is more than just doing big drops, it’s putting maximum effort in on the climbs, hitting the small drops on the trail, plowing over roots, and generally just riding hard. At what point does XC riding cross over into aggressive riding? I don’t know. I guess that point is when your equipment starts breaking or failing. That point is going to be different for different people with different riding styles.

    Even if you are not riding aggressively enough to need splined cranks for the strength aspect, consider them for the reliability aspect. How much is it worth to you not to have a ride wasted by a loose crank?

    Right now Profile has the best crank length selection for splined cranks. Profile has 145, 150, 160, 165, 170, 175, 177, and more. Unfortunately Profile is the most expensive option. I remain hopeful that KH will eventually offer more crank sizes for the KH hub. There is also the option of getting some cranks custom modified to shorten them. A couple people have gone the custom route to get specific sizes like 127 mm Profile cranks.

    The maintenance requirements for splined cranks are just different than for square tapered cranks. Splined cranks go together differently and come apart differently. You just have to learn the new system. It’s just different. I tend to make my maintenance issues more involved than normal people, but I want to find out what makes my equipment tick and I’m willing to do things like take my Profile hub apart to Loctite the keyway if it’s not feeling well.

    The cost of splined hubs and cranks is coming down. Eventually we’ll have more crank length choices for splined setups. The cost difference between the splined and square tapered setups will become less of an issue. Eventually the splined setup will become the way to go even for an entry level muni.

    9

    The Gospel According to St. John: 12:46

    10

    This sort of question always leaves me amazed and feeling a little inadequate. Here’s me riding further on a unicycle than most people ride on bicycles, ploughing through mud, grunting up hills and all that. Unicycling has put me in hospital twice in a year, and I just can’t imagine bending a crank or damaging a hub.

    Yes, I’ve seen someone leap down a flight of stairs on a uni, and someone jump off a wall. I just don’t understand why they do it on a unicycle.

    Be that as it may, and each to his own, I don’t think square taper hubs should be written off just because splined hubs are stronger. We live in a society in which we are assumed to need overspecification all the time - whether it’s the 4.2 litre 4x4 for the school run, or the titanium components saving fractions of a gramme on a bicycle belonging to someone who weighs 20 pounds more than his ideal weight. You only need the higher specification when you have exceeded the limits of the lower specification.

    I wonder how many people rely on the ‘bullet proof’ quality of their equipment rather than on finesse, balance and timing. A mate of mine at the fencing club says, “Buy the kit, get the hit.” He has 12 swords of different specifications. I can’t remember when he last beat me though.

    Tapered hubs are simple. It’s easy to swap the cranks. On those rare occasions when they work loose (anything threaded can work losse, especially when it has just been fitted) it is easy to tighten them. What’s all this stuff with grease and hammers? Just do the job carefully, that’s all it takes.

    Tchah! Young people of today… blah blah mutter mutter.

    11

    I’ve been wondering about this grease and hammering bit too.

    When I was a bike mechanic I went to a Campagnolo seminar. At the time there was somewhat of a religeous war over using grease on square taper crank fittings. One school thought that a VERY thin layer of grease was important for preventing corrosion at the steel/aluminum junction, and the other thought that dry, clean tapers gave a more reliable fitting. The Campagnolo rep said their engineers decided dry was better.

    The problem with grease is that it eliminates the friction between the crank and the spindle. (nomenclature note - if it rotates it’s a spindle, if it stays put and something rotates around it it’s an axle. Conventional unicycle wheels and cranksets have spindles, giraffe wheels and bicycle wheels have axles.) Aluminum is a material that “creeps” or slowly deforms under pressure. Most metals creep under pressure. Steel is an exception; there is a threshold level for creep with steel. Below this level it acts the same as a crystal and doesn’t creep. Above it it does.

    The classic school experiement on creep is to lay a candle down and set a brick on it. If you take the brick off right away you’ll find the candle is the same shape. Wait a month and the candle will be noticeably flattened.

    So what does this have to do with square taper crank fittings? When you first put the crank on it is tight. Over time the pressure from the crank bolt forces the crank up the taper, enlarging the crank hole and relieving the pressure. Eventually it gets a bit loose. Greasing the taper accelerates this process. Hammering the crank on creates microfractures in the aluminum that accelerate this process. Locktite by itself doesn’t do much for the strength, but I can see that it would slow the creeping process so for hard use I can see an advantage. I’d never use it on my bike cranks though. Too much of a pain, and I’ve never had a problem with cranks once I understood that they are very delicate.

    The “dry fit” school recommended cleaning off all traces of oil and grease with a solvent before fitting the crank. The “grease” school didn’t do this step. They just wiped the parts with their fingers and let the skin oils grease the taper. No one actually put grease on the tapers. (the threads in the spindle needed grease, though, otherwise torquing the bolt or nut to a given value would give an unreliable pressure on the taper.)

    The problem with a tapered fitting is that it has to be perfect to be strong. The cranking forces act at very shallow angles with respect to the faces, which means that the contact forces required are enormous. If the fit is perfect these enormous forces are applied over the full area of the face and the metal can take it. If the fit is even a bit loose then it just rounds the hole. The analogy is trying to tighten a bolt with a wrench that is a little bit large (or small for an allen wrench).

    Splined fittings have a gear-like connection with the power faces almost at right angles to the forces that have to be transmitted. This is MUCH better mechanically and keeps the stress levels lower.

    Square tapers are the historical standard and will be around for a long time, however if splined fittings had been available in the 40’s and 50’s (i.e., easier to machine than square tapers) then the standard today would be splines.

    12

    Use a crank arm puller to take square tapers off and a torque wrench to put them back on. I’ve not had any problems once I started using a torque wrench, which can be found fairly inexpensivley at Sears or at auto supply houses.

    I’m not sure what the big deal about splines is. I’ve tacoed my share of wheels, but I’ve never ruined a hub or cranks (and i only ride square tapers).

    best of luck,

    Matt

    13

    But you most likely have not Taco’d any good rims? You aren’t bending cranks because you are bending wheels.

    Get yourself an properly tensioned Alex or some other awesome wheel and you will bend cranks.

    14

    1. I think that the square tapered setup will become stronger and more reliable and not be phased out for a long, long time. I’m not really basing that on anything though, that’s just what I think.

    2. I ride with 145mm Profile cranks. I love them and don’t want ot go any longer. I like not getting my pedals caught in deep ruts and things like that. I’m going to get myself a brake as soon as possible (I have to get a new frame built first). Once that’s done my muni will be perfect for me.

    3. Splined cranks are easy to put on and take off once they’ve been worn in for a while. Initially, Profiles are really tough to remove though (without the proper tools).

    Andrew

    15

    I think the major reason people have trouble with the square taper is that they overtorque the crank nut. This ends up either stripping the threads or putting too much pressure on the axle/crank interface, resulting in premature crank loosening. Using a torque wrench at about 40 ft-lbs avoids both problems.

    If you are doing serious trials, then a splined setup is more suitable. However, any pro trials biker will tell you that he has had to work seriously on his technique in order to have the lightest gear possible and yet not ruin it. This is Mikefule’s point, and it is a fact of life in the pro trials world.

    16

    Re: Splines vs. square tapers.

    1. Yes. You can kill off a hub over time just by idling. Drops will speed up the process a lot, but I used to break my share of Suzue hubs, and I seldom did “big” drops. Big for me is 1 meter. Hubs break through metal fatigue. Because of the volume of metal involved, and the design of the interface, the splined hubs/cranks of today will take a tremendous amount more of stress before they fatigue.

    BUT. Not everybody needs splined. Here’s an easy way to tell for yourself: Break many axles?
    If no, and you don’t intend to change your riding style, you might be just fine with square tapers. It’s a pain when the hub does break, but if it only happens once in a rare while, you save money.
    If yes, get splined to save money in the long run. And hassle.

    1. Square taper hubs aren’t going anywhere. 99+% of the cycling world doesn’t need the extra strength of splined, and the square taper standard is well established. For unicycles, hopefully the price of splined parts will continue to come down. But it will be relatively slowly, because our market remains tiny.

    Splined hubs and cranks are also quite a bit more expensive to manufacture, due to the more complicated machining required. This is another reason why the above is true.

    1. My DM ATU came with 150mm splined cranks; the first ever made for unicycles (not custom, this was the standard size). That was 1999. They’re still on there, with absolutely zero maintenance, and zero creaking. If you’re in the UK especially, don’t forget about DM!

    2. I think my #1 sums it up pretty well.

    17

    DOH! Thanks for pointing that out! I wonder how many million times i’ve said that wrong.

    18

    :smiley: :smiley: :smiley:

    19

    Here’s a question that I brought up in another thread. Are there any square tapers that can compete with any splined hub/cranks? I’m guessing that the KH’s and the Profiles are pretty much in a league of their own, but how would a high-end square taper hub/crank combo compare with a low-end splined combo (e.g. the Torker DX20)?

    20

    Scott Bridgman sells what he says is a bombproof hub, but it does require a lot of special provisions, including that you have to have your cranks modified, and that he has to press on your cranks before the wheel is built. That hub with a pair of Kookas should be pretty strong, although I have not heard any independent test results.